Endangered Species in the Pacific Islands

Mariana Common Moorhen / Gallinula chloropus guami / Pulattat

The Mariana Islands subspecies of the common moorhen resembles other moorhen subspecies found throughout the world. The Mariana common moorhen is a slate-black bird about 14 inches (35 centimeters) in length. The distinguishing physical characteristics of adult birds include a red bill and frontal shield, white undertail coverts, a white line along the flank, and long olive-green legs with large unwebbed feet.

Males and females are nearly identical in appearance and are difficult to distinguish from each other.

Mariana moorhen - Photo credit USFWS

Habitat & Behavior:
The Mariana common moorhen is also known in the native language as Pulattat.

Moorhens in the Mariana Islands are found primarily at freshwater natural and artificially created wetlands that are both seasonal and permanent. Occasionally, they are recorded in brackish water wetlands. Wetlands that support about equal amounts of emergent, submergent, and/or floating vegetation and open water are more suitable to moorhens for feeding, nesting, and loafing than wetlands that are predominately open water or that support mostly emergent wetland vegetation. In the Mariana Islands, moorhens have been recorded at golf course wetlands, commercial fish ponds, sewage treatment plants, wetlands created for the mitigation of wetland loss, as well as at natural wetlands.

Nests have been found in all months of the year. They are typically concealed in emergent vegetation near open water, but some nests are constructed out in the open on submergent vegetation beds or on floating debris. Most active nests contain six eggs that are buff-colored with dark speckles. Eggs are between 41-44 millimeters in length and 30-32 millimeters in width. Incubation lasts 19-21 days.

Mariana common moorhens feed on a variety of plant and animal matter that may be located in the water, in and adjacent to wetland vegetation, and along the shoreline.

Moorhens in the Mariana Islands move from seasonal to permanent wetlands during the dry season (January to April) and then move back to seasonal wetlands during the rainy season (July to November). They also fly between islands to utilize seasonal and permanent wetlands.

Past & Present:
Historically, the Mariana common moorhen was found on the islands of Guam, Tinian, Saipan, Rota, and Pagan. The Pagan population is believed extinct due to ash and cinder fallout from a 1981 eruption of Mount Pagan and overgrazing and rooting of emergent vegetation by feral cattle and pigs.

It is likely that moorhens in Mariana Islands were historically more numerous and perhaps more widely distributed than they are today. Wetland loss, sedimentation and siltation, urbanization, introduced predators including brown treesnakes, feral ungulates, introduced fish, and encroachment of wetland vegetation are some of the threats that have and continue to impact moorhens and wetland habitats in the Mariana Islands.

Present populations are estimated to be between 100-150 birds on Guam, 50 birds on Tinian, 100 birds on Saipan, and fewer than 10 birds on Rota. Based on surveys conducted in 2001, it appears that the number of birds on Guam has declined, particularly at Fena Lake.

Conservation Efforts:
As a Federally listed endangered species (August 27, 1984), the Mariana common moorhen is afforded the protections and provisions under the Endangered Species Act of 1973, as amended, and the Migratory Bird Treaty Act. It is also protected by the Territory of Guam Endangered Species Act and Commonwealth of the Northern Mariana Islands wildlife regulations. Section 404 of the Clean Water Act of 1977 provides regulations for the protection of wetlands. This law provides some protection for moorhen habitat.